1. Field of the Invention
This invention relates generally to control cable tension regulation and, more particularly, no control cable tension regulation in aircraft. Although the present invention finds particular utility in aircraft, it is to be expressly understood that the advantages of the invention are equally well manifest wherever it is desired to closely regulate the tension of a control cable, i.e. a cable capable of transmitting a control function.
2. Background of the Invention
It is known to use control cables to connect flight control surfaces with the control column in an aircraft. In this way, movement of the column by the pilot is transmitted to the control surfaces to provide aircraft attitude and direction control. Due to the limited amount of space available within the aircraft and to the physiological limitations of maximum comfortable pilot movement, input motion into the control system is limited. It is, therefore, very important to efficiently transmit this motion to the flight control surfaces by holding control signal losses, e.g., through cable stretch and system friction, to a minimum. This has become more difficult as aircraft have increased in size, and control cables have lengthened proportionally. Additional losses may be incurred due to the fact that the control cables are also subject to thermel affects and to added friction caused by deflection of the airframe along which they are mounted. To provide the desired precise response, cables are often placed under an appropriate tension which must be maintained for proper system performance.
Various types of mechanical tension regulators have been used to compensate for cable stretch and maintain the desired cable tension. These devices are severely limited in the amount of regulation movement they can provide. Once this limit is exceeded, the entire system must be re-rigged, which is a costly and time consuming process.
Since control cables are usually run in pairs to provide both positive and negative control surface deflection, cable tension arrangements must provide some means to sense cable failure, be responsive to such failure and prevent runaway regulation. This problem becomes even more critical as the amount of available regulation movement increases. Mechanical regulators frequently use a differential locking mechanism to prevent runaway regulation. These devices, however, tend to place an amount of undesirable backlash in the system, which, under certain conditions can cause slippage.
Initial rigging of a mechanically regulated system is a complex and time consuming process due to their limited regulation capability. Also, substantially the same difficulty is encountered each time re-rigging is required.
Accordingly, it is an object of the invention to provide a control cable tension regulation process and system that overcomes the disadvantages and limitations of the prior art.
It is another object of the invention to provide a control cable tension regulation system that is self-rigging at installation.
It is a further object of the invention to provide a control cable tension regulation process and system that provides increased regulation movement and improved mechanical advantage over friction.
Another object of the invention is to provide a control cable tension regulation system that produces no slip or backlash in the control mode and yet prevents runaway regulation.
It is a further object of the invention to provide a servo-type control cable tension regulation system that reduces the need for rigging maintenance.